.container {
    padding: 15px;
    line-height: 2;
}

.round {
    display: block;
    position: fixed;
    right: 25px;
    width: 60px;
    height: 60px;
    border-radius: 50%;
    background-color: #000;
    opacity: .6;
}

.s-top-but {
    display: none;
    bottom: 100px;
    background: url(../img/rocket.png) no-repeat 0 0/100% 100%;
}

.play-btn {
    bottom: 25px;
    background: orange url(../img/play.png) no-repeat 15px 15px/30px 30px;
}

.round:hover {
    opacity: 1;
}